Study: Maternal Asthma Increases Incidence of Adverse Perinatal Outcomes

Asthma is a chronic respiratory disease, causing inflammation and restriction of the airways within the lungs. Shortness of breath is already a common symptom of pregnancy, but women with asthma may experience an exacerbation of symptoms such as wheezing, coughing, and chest tightness. All of these contribute to an increase in adverse perinatal outcomes for the fetus and mother.¹

Image credit: sosiukin | stock.adobe.com

Few studies research maternal asthma’s effects on perinatal outcomes, leaving gaps in knowledge about this condition and its management. However, a recent study based in Alberta, Canada, examined the associated risk of preterm birth (PTB, gestational age <37 weeks), low birth weight (LBW, ≤2500 g [5.5 pounds]), and cesarean delivery.²

This retrospective study includes a substantial cohort of 434,068 singleton pregnancies from October 2009 through December 2018. In this study, 8.6% of women had asthma at any point during their life, including a history of asthma (52%), current asthma (40%), or active disease (7%).²

Diagnosing maternal asthma early in pregnancy is important for optimal outcomes for both mother and baby. Overall, maternal asthma was associated with a 15% increased risk of PTB, 12% increased risk of LBW, and 9% increased risk of cesarean delivery. When evaluating maternal asthma status of historical, current, and active disease at delivery, those with active disease often had the highest risk of PTB, LBW, and cesarean delivery.²

Asthma presents a multitude of different phenotypes, which is important to consider if there is ongoing inflammation. The study focused on phenotyping based on inflammatory cell types, classified as low or high blood eosinophils (LBE, HBE) and low or high blood neutrophils (LBN, HBN). Patients with a phenotype group of HBE/HBN have the highest risk PTB, LBW, and cesarean delivery.²

Medication use in those with maternal asthma varies greatly. Sixty-six percent of women with a history of asthma, 19% of women with current asthma, and 36% with active disease do not take medication.²

Common medications used for asthma include oral corticosteroids (OCS), inhaled corticosteroids (ICS), long acting β₂ adrenergic receptor agonists (LABA), and short acting β₂ adrenergic receptor agonists (SABA). Prednisone, prednisolone, and methylprednisolone are common OCS medications used in pregnant women, and budesonide is a preferred ICS. LABA options may include salmeterol or formoterol with albuterol often prescribed in the SABA class.³

Women with a history of asthma had a 31% increased risk of PTB when prescribed OCS plus an ICS with a LABA or SABA. In those prescribed only OCS, a 37% increased risk of PTB was determined. The risk was more elevated in those with active asthma, and patients with current asthma fall in the middle in terms of risk.²

Patients with a history of asthma on OCS alone were determined to have a 40% increased risk of LBW, whereas there was no significant risk found in those with current diagnosis or active asthma. Patients with current asthma prescribed OCS plus an ICS with a LABA or SABA were shown to have a 37% risk increase, while those with active asthma had a 2-fold increased risk of LBW.²

Of important note, asthmatic patients living in a more urban area and those without prenatal education showed significantly increased risks of PTB, LBW, and cesarean delivery.²

Based on these findings, the authors concluded that additional monitoring and a review of current treatments are necessary due to the increased risk of adverse perinatal outcomes. Maternal asthma treatment guidelines may need to be updated to include the latest information.²

REFERENCES

1. Asthma & Pregnancy. Cleveland Clinic. Updated September 5, 2023. Accessed June 1, 2025. https://www.dynamed.com/condition/asthma-during-pregnancy#ORALSTEROIDS

2. Moitra S, Savu A, Annesi-Maesano I, et al. Maternal asthma and adverse perinatal outcomes: An analysis of 434,068 pregnancies in Canada. J Allergy Clin Immunol Pract. 2025;S2213-2198(25)00415-5. doi:10.1016/j.jaip.2025.04.046

3. Asthma during pregnancy. In: DynaMed [online database]. EBSCO Information Services. Updated August 30, 2024. Accessed May 31, 2025. https://www.dynamed.com/condition/asthma-during-pregnancy#ORALSTEROIDS